Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to uplink data routing.
Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the UMTS Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP). The UMTS, which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband-Code Division Multiple Access (W-CDMA), Time Division-Code Division Multiple Access (TD-CDMA), and Time Division-Synchronous Code Division Multiple Access (TD-SCDMA). The UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSPA), which provides higher data transfer speeds and capacity to associated UMTS networks. High Speed Uplink Packet Access (HSUPA) is a protocol of HSPA that provides an enhanced dedicated uplink channel (E-DCH) that allows an option for selecting a transmission time interval (TTI) (e.g., 2 ms or 10 ms), and a media access control (MAC) sublayer to process scheduling of uplink transmissions and hybrid automatic repeat request (HARQ) signals.
As the demand for mobile broadband access continues to increase, research and development continue to advance the UMTS technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications.
In current HSPA systems, a user equipment (UE) may transmit uplink physical channels over multiple carriers that may include a dedicated physical control channel (DPCCH). If there is a power imbalance among the multiple carriers, call drops and severe throughput degradation may result. For example, depending on the channel condition, there could be a large power difference on the DPCCH of each carrier in HSUPA since the inner loop power control of the carriers is allowed to be independently controlled by an eNode B. This power level difference is called DPCCH power imbalance. In the case of the call drop with the DPCCH power imbalance, data throughput is degraded first, and call drop happens if the critical data did not go through even after high layer retransmission. The uplink degradation may be caused by sudden and deep channel fading, too much interference from other UEs, E-DCH power compression due to excessive transmit power at the UE, and low signal-to-noise ratio. As such, improvements in transmitting uplink physical channels over multiple carriers are desired.